Last week Patently Apple posted a report titled "A new Apple patent application reveals their ongoing work on a solution to place cameras under the display of devices." Today, the U.S. Patent and Trademark Office officially granted Apple a patent that advances this potential future feature.

Technically relates to displays with associated sources and sensors of optical radiation that could be used on the iPhone but also on future smartglasses. More importantly, Apple notes that "One or more diffractive structures are formed in the planar optical waveguide so as to couple the guided second optical radiation between the planar optical waveguide and a region in front of or behind the display."

Apple first notes that traditional sensing systems in portable devices comprise modules performing functions such as illumination, ambient light sensing, image capture, gesture recognition, and proximity sensing. Each type of module typically contains a lens assembly, as well as illumination and/or sensing devices that emit or receive optical radiation within different spectral regions through a variety of physical apertures located within the portable devices. These modules compete for space with the display (or displays) of the portable device, and may increase, for example, the physical size of a smartphone or the frame thickness of AR glasses.

Apple's granted patent address these problems by providing a planar optical waveguide that is overlaid on the display of a portable device, which guides radiation across the surface of the display without interfering with the display functionality.

The waveguide can be coupled to a functional module, such as an emission source, comprising one or more emitters, or a photodetection module, comprising one or more sensors (or both), which is typically located outside the display area, in order to guide radiation to or from the module.

A functional module comprising the planar waveguide, diffractive structures, emitters, and/or sensors can perform one or more functions of the portable device, such as emitting flood and/or structured illumination, ambient light sensing (ALS), image sensing, three-dimensional (3D) mapping, motion sensing, and gesture recognition.

Today, the flood illuminator, ambient light sensor and depth camera are in the "notch" area of the iPhone for Face ID. Today's granted patent claims that these sensors could be placed elsewhere under the display as presented in patent FIG. 3 below to perform Face ID.

In FIG. 3, an iPhone (device #20) captures a 3D map of the owner #50. Radiation emitted by the emitter (not shown) is radiated out of waveguide #24 by diffractive structure #30 as structured light, for example as discrete beams #60, projecting spots #62 onto the owner's face. The iPhone's controller finds the distance of each spot from the iPhone by triangulation, and in this way constructs a 3D map of the owner's face.

Further, by 3D mapping of, for example, a hand of the owner over several consecutive image frames, the movements of the hand in 3D space may be recorded for gesture recognition. 

Lastly, Apple's patent FIG. 4 above is a schematic sectional view of an illumination module overlaid on the front surface of a display.

For more details, review Apple's granted patent 11754767.